分类： 物理学 >> 核物理学 提交时间： 2024-01-02
摘要： The aging of operational reactors leads increased mechanical vibrations of reactor internals. The vibration of the in-core sensors near their nominal locations is a new issue for the neutronic fields reconstruction. Current field reconstruction methods fail to handle spatially moving sensors. In this work, we proposed a Voronoi tessellation techinque in combination with convolutional neural networks (V-CNN) to handle this challenge. The observations from movable in-core sensors are projected to the same global field structure, this projection is achieved with Voronoi tessellation, holding the magnitude and location information of sensors. The general convolutional neural networks were used to learn the map from observations to the global field. The proposed method is able to reconstruct the multi-physics fields (e.g., the fast flux, thermal flux and power rate) using observations from single field (e.g., thermal flux). Numerical tests based on IAEA benchmark proved its potential for real engineering usage, particularly, within an amplitude of 5 cm around nominal locations, the field reconstruction leads to average relative errors below 5 % and 10 % in $L_2$ norm and $L_{ infty}$ norm, respectively.
分类： 物理学 >> 核物理学 提交时间： 2023-11-18
摘要： The estimation of model parameters is an important subject in engineering. In this area of work, the prevailing approach is to estimate or calculate these as deterministic parameters. In this study, we consider the model parameters from the perspective of random variables and describe the general form of the parameter distribution inference problem. Under this framework, we propose an ensemble Bayesian method by introducing Bayesian inference and the Markov chain Monte Carlo (MCMC) method. Experiments on a finite cylindrical reactor and a 2D IAEA benchmark problem show that the proposed method converges quickly and can estimate parameters effectively, even for several correlated parameters simultaneously. Our experiments include cases of engineering software calls, demonstrating that the method can be applied to engineering, such as nuclear reactor engineering.
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